tailieunhanh - Chemical Degradation Methods for Wastes and Pollutants - Chapter 3

Siêu tới hạn nước oxy hóa Quá trình oxy hóa nước siêu tới hạn (SCWO) là một công nghệ xử lý chất thải sử dụng nước siêu tới hạn như một phương tiện để oxy hóa chất hữu cơ. SCWO cũng có thể được mô tả như một phần mở rộng của quá trình oxy hóa dưới tới hạn, không khí ẩm ướt quá trình oxy hóa (WAO) quá trình, hoặc được biết đến rộng rãi quy trình Zimpro [1] .* Cả hai quá trình (SCWO và WAO) liên quan đến việc quy tụ chất thải hữu cơ, nước, và một chất oxy hóa (chẳng hạn. | 3 Supercritical Water Oxidation Technology Indira Jayaweera SRI International Menlo Park California . I. INTRODUCTION Supercritical water oxidation SCWO is a waste treatment technology that uses supercritical water as a medium for oxidizing organic material. SCWO can also be described as an extension of the subcritical oxidation process wet air oxidation WAO process or widely known Zimpro process 1 . Both processes SCWO and WAO involve bringing together organic waste water and an oxidant such as air or oxygen to elevated temperatures and pressures to bring about chemical oxidations. Generic operational conditions for the two processes are as follows WAO 150-300 C 10-200 bar SCWO 374-675 C 220 bar. Fig. 1 shows a graphical representation of these operational regions. WAO and SCWO processes are often referred to as hydrothermal oxidation technologies HTOs . The major difference between the processes is that in SCWO organics are completely oxidized in a relatively short time seconds to minutes whereas in WAO the reaction may require a longer time minutes to hours . Furthermore in WAO some refractory organics are not completely oxidized because of the lower temperature of operation The pioneering work of Fred Zimmerman in the 1950s led to the creation of the Zimpro process 1 . Copyright 2003 by Marcel Dekker Inc. All Rights Reserved. Figure 1 Phase diagram for pure water. Solid line liquid-gas equilibrium. 350 C thus requiring a secondary treatment process. As information on WAO technology is readily available from other sources 2-5 the SCWO process is mainly discussed here. The SCWO process is ideal for the disposal of many aqueous hazardous materials . EPA priority pollutants industrial wastewater and sludges municipal sludges agricultural chemicals and laboratory wastes but has also been demonstrated to effectively destroy military wastes . ordnance rocket propellants and chemical agents 6-18 . The effluent from the SCWO process consisting primarily of .